JPH0584168B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an underwater electrode for non-contact stone crushing.

[Conventional technology]

Stones in the human body can be broken up non-contact into excretable fragments by mechanical shock waves. Shock wave generation is performed by underwater spark discharge, where the electrode is at the focal point of a spheroidal water-filled focusing chamber, and the electrode energy stored in the capacitor is converted into shock wave energy by the spark discharge. converted.

An electrode used to generate shock waves of this type is known from German Patent No. 26 35 635. In particular, the electrode shown in FIG. 4 of that publication is actually well received. In this electrode, the tubular outer conductor transitions into a yoke or cage, at the tip of which is fixed an electrode tip, which is located axially opposite the other electrode tip connected to the inner conductor. There is.

The concentric arrangement of the electrodes provides a constant boundary range of the field line starting from the inner conductor and ending at the outer conductor, the outer conductor cage and the outer conductor tip. The jump of the spark should be carried out as far as possible along the electrode axis for focusing by the ellipsoid. This can no longer be guaranteed in the event of advanced electrode wear. It first separates and then becomes a "misfire", which is a discharge in the formation of multiple plasma channels. This “misfire”
is perceived as a weak acoustic shock. If this occurs frequently, the electrodes are replaced.

[Problem that the invention seeks to solve]

An object of the present invention is to extend the life of underwater electrodes for non-contact stone crushing.

[Means for solving problems]

According to the invention, this object is achieved in that at least one electrode tip is arranged with a bush or blind made of dielectric material.

[Effect]

By utilizing a second dielectric (other than water) in the form of a bush or blind, the life of the electrode is considerably extended. As a result of the experiment, it was confirmed that the lifespan was tripled. In the present invention, the field line refraction effect in the boundary layer of a second dielectric having a different dielectric constant is utilized. Since water with ε = 80 has a much larger dielectric polarization than a solid dielectric, we decided to add a geometrically appropriately formed dielectric with a small dielectric polarization (ε = 2-3). Therefore, the field line distribution between the electrode tips is favorably influenced. The jump of the spark is advantageously made on the electrode axis, so that the local focus of the spark is only slightly scattered around the upper focal point.

Advantageous embodiments of the invention are described in the subclaims.

〔Example〕

The present invention will be described in detail below with reference to embodiments shown in the drawings.

FIG. 1 shows an underwater electrode 2 for generating shock waves used for non-contact stone crushing. This electrode consists of an inner conductor 4 having an electrode tip 6, an insulator 8, and an outer conductor 1.
0 and an assembly bush 12.

The electrode 2 is fastened to an electrode holder (not shown) by means of an assembly bush 12, and at the same time the inner conductor 4 and the outer conductor 10 are connected to an electrical system (not shown).

A cage 14 is fixed to the outer conductor 10,
This cage 14 consists of a plurality of wires 15 and supports a second electrode tip 16. A protective hose 18 made of synthetic resin is partially placed over the wire 15.

The inner conductor 4 and the outer conductor 10 are made of metal material. Electrode tip 16 is made of tungsten, tantalum or another flame resistant material or alloy. The insulator 8 and the assembly bush 12 are made of synthetic resin.

In FIG. 1, a bush 2 is placed on the electrode tip 6.
0 is shrink-fitted. The bush 20 is made of a material that is resistant to impact and has a suitable dielectric constant. An example of this material is "Pocan"(Leverkusen's
Firma Bayer (product name) is suitable. In use, this material has the same acoustic properties as water, allowing sound to pass through and avoiding refraction and dispersion of shock waves. The inner circumferential surface 22 and the outer circumferential surface 23 of the bush 20 have a conical shape, and the end surface 24 is flat in this embodiment. The bush 20 is integral with the insulator 8.

Figure 2 shows, in addition to the structural parts shown in Figure 1,
The dielectric bushing 26 on the electrode tip 16 is shown. The geometry and wall thickness of the electrode bushes 20, 26 are designed in such a way that an optimum field line path is produced.

For this purpose, for example, as can be seen in FIG. 3, the end faces 28, 30 of the bushes 20, 26 are designed to be convex or concave. Also in this embodiment, the bushings are shrink-fitted onto the electrode tips 6, 16.

FIG. 4 shows a dielectric ring 32 with holes 34 secured to the cage 14. this ring 3
2 is formed into a lens shape. It is also possible within the framework of the invention to vary the shape and manner of fastening of the ring 32.

[Brief explanation of the drawing]

Figure 1 is a cross-sectional view of an electrode with a dielectric bushing on one electrode tip, Figure 2 is a cross-sectional view of an electrode with dielectric bushings on both electrode tips, and Figure 3 is a cross-sectional view of an electrode with dielectric bushings on both electrode tips. FIG. 4 is a cross-sectional view of an electrode with a dielectric bush formed thereon; FIG. 4 is a cross-sectional view of an electrode with a dielectric ring formed thereon; 2... Electrode, 6... Electrode tip, 14... Cage, 16... Electrode tip, 20... Bush, 24
...Button end face, 26...Button, 28...
...Bushy end face, 30...Bushy end face, 32...
…ring.

Claims (1)

[Claims] 1. In an underwater electrode for non-contact stone crushing in which two electrode tips are located facing each other, at least one electrode tip 6, 16 is provided with a bush 20, 26 or a ring made of a dielectric material. An underwater electrode for non-contact stone crushing, characterized in that: 32 is arranged. 2. The underwater electrode according to claim 1, wherein the end surface 24 of the bush 20 is flat. 3. The underwater electrode according to claim 1, wherein the end surfaces 28, 30 of the bushes 20, 26 are convex or concave. 4 End face 2 of the bush at one electrode tip 6
8 is a convex surface, and the end surface 30 of the bush at the other electrode tip 16 is a concave surface. 5. The underwater electrode according to claim 1, wherein the ring 32 is fixed to the cage 14 or the electrode tips 6, 16. 6. The underwater electrode according to claim 5, wherein the ring 32 is formed in a circular, lens-shaped, rectangular shape, or a combination of convex and concave surfaces.